//
// UUIDGenerator.h
//
// Library: Foundation
// Package: UUID
// Module:  UUID
//
// Definition of the UUIDGenerator class.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef Foundation_UUIDGenerator_INCLUDED
#define Foundation_UUIDGenerator_INCLUDED


#include "Poco/Environment.h"
#include "Poco/Foundation.h"
#include "Poco/Mutex.h"
#include "Poco/Random.h"
#include "Poco/Timestamp.h"
#include "Poco/UUID.h"


namespace Poco
{


class DigestEngine;


class Foundation_API UUIDGenerator
/// This class implements a generator for Universal Unique Identifiers,
/// as specified in Appendix A of the DCE 1.1 Remote Procedure
/// Call Specification (http://www.opengroup.org/onlinepubs/9629399/),
/// RFC 2518 (WebDAV), section 6.4.1 and the UUIDs and GUIDs internet
/// draft by Leach/Salz from February, 1998
/// (http://ftp.ics.uci.edu/pub/ietf/webdav/uuid-guid/draft-leach-uuids-guids-01.txt)
{
public:
    UUIDGenerator();
    /// Creates the UUIDGenerator.

    ~UUIDGenerator();
    /// Destroys the UUIDGenerator.

    UUID create();
    /// Creates a new time-based UUID, using the MAC address of
    /// one of the system's ethernet adapters.
    ///
    /// Throws a SystemException if no MAC address can be
    /// obtained.

    UUID createFromName(const UUID & nsid, const std::string & name);
    /// Creates a name-based UUID.

    UUID createFromName(const UUID & nsid, const std::string & name, DigestEngine & de);
    /// Creates a name-based UUID, using the given digest engine.
    ///
    /// Note: in order to create a standard-compliant UUID, the given DigestEngine
    /// must be either an instance of MD5Engine or SHA1Engine. The version field of
    /// the UUID will be set accordingly.

    UUID createFromName(const UUID & nsid, const std::string & name, DigestEngine & de, UUID::Version version);
    /// Creates a name-based UUID, using the given digest engine and version.

    UUID createRandom();
    /// Creates a random UUID.

    UUID createOne();
    /// Tries to create and return a time-based UUID (see create()), and,
    /// if that does not work due to the unavailability of a MAC address,
    /// creates and returns a random UUID (see createRandom()).
    ///
    /// The UUID::version() method can be used to determine the actual kind of
    /// the UUID generated.

    static UUIDGenerator & defaultGenerator();
    /// Returns a reference to the default UUIDGenerator.

protected:
    Timestamp::UtcTimeVal timeStamp();
    void getNode();

private:
    FastMutex _mutex;
    Random _random;
    Timestamp _lastTime;
    int _ticks;
    Environment::NodeId _node;
    bool _haveNode;

    UUIDGenerator(const UUIDGenerator &);
    UUIDGenerator & operator=(const UUIDGenerator &);
};


} // namespace Poco


#endif // Foundation_UUIDGenerator_INCLUDED
